On Mon, 29 Sep 2003, James V wrote:

> what exactly is happening that makes the AFM go nutty???!

Ever had a radio with a bad volume control?  You know, one with a bad spot
that would create lots of static as the control moved past it, or drop out
entirely?

I think that's what happens with the AFM.

Over time the resistance element wears out in areas where the AFM wiper
spends a lot of time.  The ECU then gets incorrect or nonexistant AFM
readings at those positions, causing the engine to run badly.  Some people
with bad AFMs have described an inability to hold certain engine speeds,
while the engine would run fine at other speeds, which fits with this
explanation.

Hondas from Great Plains states exhibit a similar problem with their
throttle position sensors.  The car spends most of its time going 70 mph
on flat ground, often on cruise control, with the throttle moving in a
very small range, and the sensor eventually wears out in that area.  The
car then bucks and misses whenever the throttle moves through that bad
spot.

David Brodbeck, N8SRE
'82 Diesel Westfalia
'94 Honda Civic Si